Isabelle Vea: Sussing out Scale Insect Evolution at the Museum

On September 30, 2013, the first graduates of the Richard Gilder Graduate School will receive Doctor of Philosophy degrees in Comparative Biology at the inaugural commencement for the first Ph.D.-granting program for any museum in the Western hemisphere. We're profiling the newly minted Ph.D.s this week.

Throughout her life, Isabelle Vea has lived in and travelled to many exciting places. Among the first students to graduate from the Museum’s Richard Gilder Graduate School, Vea grew up and attended college in Paris, where she also received a master’s degree from the famed Muséum National d’Histoire Naturelle; studied Mandarin Chinese in China for a year; and has spent the past four years in Manhattan, analyzing scale insects at the Museum.

Belonging to the order Coccoidea, scale insect species living today number about 8,000; they are often crop pests, but little has been known about their evolution. For her dissertation, Vea produced a timed phylogeny—that is, a “tree” of evolutionary relationships placed within a time scale—of the superfamily, the first such assessment of the relationships between fossils and recent species in scale insects.

Scale insects are very small, ranging in size from 1 to 3 millimeters. In this SEM (scanning electron microscope) image taken at the Museum's Microscopy and Imaging facility, you can see that this adult male from the genus Callipappus has no mouth (look between the eyes). As adults, in fact, no male scale insect has mouthparts; they do not feed but instead live a short time in order to reproduce.

Courtesy of Isabelle Vea

As part of the work, Vea worked with her adviser David Grimaldi, a professor in the Richard Gilder Graduate School and curator in the Division of Invertebrate Zoology, to study the evolutionary relationships of both living species and extinct forms of a smaller group of coccoids, the family Ortheziidae, some of which are about 95 million years old and have been preserved in amber. Among fossil scale insects, males of the species are more likely to fossilize, but in this particular family, the females were preserved in the fossil record.

Prior to conducting her research, Vea hypothesized that scale insect species might have diversified starting at the same time—about 130 million years ago—as the flowering plants (angiosperms) that living scale insect species feed on today. Instead, however, “Isabelle's work found that the group largely diversified before the angiosperms did...” notes her adviser, David Grimaldi. “Scales must have evolved with conifers and other gymnosperms, then shifted onto angiosperms—an insight that could only be derived from study of the fossil record.”

Isabelle Vea in Costa Rica, 2010, on a trip conducting field research

Courtesy of Isabelle Vea

In addition to studying the Museum’s exceptional amber collections, Vea conducted her own fieldwork collecting modern specimens in France, Croatia, Florida, and New Mexico, as well as at the Museum’s Southwestern Research Station, in Arizona. For Museum coursework, she also travelled to Costa Rica and Mexico.

Having studied the evolution of scale insects, Vea will head to yet another farflung destination—to the University of Nagoya, Japan, about 2.5 hours south of Tokyo—where a postdoctoral fellowship from the Japanese Society for the Promotion of Science will enable her to undertake novel developmental biology research on living scale insects to better understand how males metamorphose.